What is a good age to start a 16m for swimming classes?

My sister's daughter started swimming when she 14 months and she was quite a water baby and took to the pool like fish takes to water. However, it would be better if you consult a professional who would be able to guide you on the kind of swimming class that your baby should take and for how much duration. As your baby is only 16 months, don't be too harsh on him as his muscles and bones are still fragile and developing.